1. Field of the Invention
The present invention relates to a switch device for operating, for example, an audio system, an air conditioning system and so on in a vehicle. More particularly, the present invention relates to a switch device employing key members each capable of transmitting image information, displayed on a display screen of an image display device, therethrough so as to display this image information on an outer side (outer surface) of the key member.
The present application is based on Japanese Patent Application No. Hei. 11-213930, which is incorporated herein by reference.
2. Description of the Related Art
In most of conventional switches used, for example, in an on-board radio cassette deck, characters or the like, indicating button functions, are printed directly on operating buttons. Therefore, in a multi-function radio cassette deck or the like, it has been necessary to prepare the operating buttons in accordance with the various functions, and it has also been necessary to indicate two functions on one operating button by printing.
With this construction, however, the number of the operating keys increases, so that the equipment (radio cassette deck or the like) has an increased size, and besides a plurality of functions are indicated by printing on the same operating button, which invites a problem that the characters or the like thereon can not be clearly recognized.
In order to solve these problems, there has been proposed a switch device in which operating buttons, each having a transparent window portion, are arranged on a display screen of a liquid crystal display, and button function-indicating characters or the like, displayed on the display screen, are transmitted through the transparent window portion to the outer side of the operating button. Such a switch device is disclosed, for example, in Unexamined Japanese Patent Publication No. Hei. 9-198176.
As shown in FIG. 11, in such an electronic equipment, a liquid crystal display 102 and a switch 103 are mounted on a printed circuit board 101, and a front panel 104 is provided to cover the liquid crystal display 102 and other parts, and operating buttons 106, each having a transparent window portion 105, are mounted on the front panel 104. Button function-indicating characters or the like, displayed on a display screen 107 of the liquid crystal display 102, are displayed on the outer side (outer surface) of the operating button 106 through the transparent window portion 105.
In the electronic equipment of the above construction, a receive frequency, an operating condition and so on are displayed on an upper portion of the display screen 107 whereas the button functions of the operating buttons 106 are displayed on a lower portion of the display screen 107, and this displayed button function can be recognized through the transparent window portion 105 with the eyes.
Therefore, in this electronic equipment, it is not necessary to indicate the button functions on the operating buttons by printing, and the functions of the operating buttons can be indicated, utilizing the display device for displaying the operating condition of the equipment and so on. And besides, each operating button can have a plurality of functions (to provide a so-called multi-switch design), and therefore it is not necessary to increase the number of the operating buttons, and the switch device can have a compact size.
In the electronic equipment of the above construction, however, when dirt, dust, a water droplet or other foreign matter, intrudes into the interior of the switch device through a gap between the operating buttons 106, and is disposed between the display screen 107 and the operating button 106, the user can recognize this foreign matter (such as dust, dirt and a water droplet) through the transparent window portion 105. Namely, part of the operating button 106 is transparent, and therefore there is a drawback that the foreign matter (such as dust, dirt and a water droplet), which has intruded into the interior, can be viewed. In addition, there is not provided any means which enables the use to remove the foreign matter (such dust and dirt) which has intruded into the gap between the display screen 107 and the operating button 106.
Therefore, the present invention has been made in order to solve the above problems, and an object of the present invention is to provide a switch device in which a foreign matter (such as dust, dirt and a water droplet) is positively prevented from intruding into a gap between an display switch button and a display screen from the outer periphery of the display switch button.
To achieve the above object, according to the first aspect of the present invention, there is provided a switch device which comprises a key member located above a display screen of an image display device which is capable of displaying image information on the display screen, the key member being capable of transmitting the image information therethrough so as to display the image information on an outer side surface thereof, the key member comprising a display switch button, a button mounting frame, which includes a switch depressing portion operative to switch a switch when the key depressing portion is depressed, and which has a button mounting hole portion to which the display switch button is attached, and a waterproof dust cover of a rubber material, which is molded integrally on the button mounting frame to cover the button mounting frame, and which includes a support portion held in intimate contact with the display screen, and a contractible skirt portion, wherein a plurality of resin filling holes are formed in the button mounting frame, and wherein the rubber material, forming the waterproof dust cover, is filled in the resin filling holes.
Accordingly, since the support portion of the waterproof dust cover is held in intimate contact with the display screen, the waterproof dust cover prevents the intrusion of a foreign matter, such as dust, dirt and a water droplet, into a gap between the display screen and the display switch button.
In the above construction, the plurality of resin filling holes are formed in the button mounting frame, and the rubber material, forming the waterproof dust cover, is filled in the resin filling holes. With this construction, the button mounting frame of the resin and the waterproof dust cover of the rubber material, which are usually not bonded together, are firmly combined together to provide an integral construction. Thus, the button mounting frame and the waterproof dust cover are combined into an integral construction, and therefore the efficiency of the assembling operation is enhanced.
According to the second aspect of the present invention, the display switch button may include a transparent portion through which the image information is transmitted so as to display the image information on the outer side surface of the key member.
According to the third aspect of the present invention, it is preferable that the button mounting frame is associated with the display switch button to switch the switch.
According to the fourth aspect of the present invention, it is preferable that the display switch button is press-fitted in the button mounting hole portion covered with the rubber. The display switch button is press-fitted in the button mounting hole portion covered with the rubber, and therefore the display switch button is held in intimate contact with the rubber at this press-fitted portion, so that the intrusion of a foreign matter, such as dirt, dust and a water droplet, through this press-fitted portion, is prevented.
According to the fifth aspect of the present invention, it is preferable that a heat-resistance temperature of a resin material, forming the button mounting frame, is higher than a heat-resistance temperature of the rubber material forming the waterproof dust cover. The button mounting frame is formed by the resin material whose heat-resistance temperature is higher than that of the rubber material forming the waterproof dust cover, and therefore the integrally-molded structure can be obtained in a rubber-molding mold. And besides, the display switch button is prevented from becoming uneven in thickness, and therefore the molding can be carried out easily. Generally, a transparent resin material exhibits a low resistance to an impact, and therefore the reliability of the switch itself can be enhanced by the use of the separate button mounting frame.
Furthermore, to achieve the above object, according to the sixth aspect of the present invention, there is provided a switch device which comprises a key member located above a display screen of an image display device which is capable of displaying image information on the display screen, the key member being capable of transmitting the image information therethrough so as to display the image information on an outer side surface thereof, the key member comprising a display switch button, a button mounting frame, which includes a switch depressing portion operative to switch a switch when the key depressing portion is depressed, and which is molded integrally on an outer periphery of the display switch button, and a waterproof dust cover of a thermoplastic elastomer, which is molded integrally on the button mounting frame to cover the button mounting frame, and which includes a support portion held in intimate contact with the display screen, and a contractible skirt portion, wherein a plurality of resin filling holes formed in the button mounting frame, and the thermoplastic elastomer is filled in the resin filling holes. Accordingly, since the support portion of the waterproof dust cover is held in intimate contact with the display screen, the waterproof dust cover prevents a foreign matter, such as dust, dirt and a water droplet, from intruding into the gap between the display screen and the display switch button. Furthermore, since the waterproof dust cover is made of the thermoplastic elastomer, the display switch button and the button mounting frame, which are integrally molded together, will not melt when molding the waterproof dust cover.
The plurality of resin filling holes are formed in the button mounting frame, and the thermoplastic elastomer, forming the waterproof dust cover, is filled in the resin filling holes. Therefore, the button mounting frame of the resin and the waterproof dust cover of the rubber material, which are usually not bonded together, are firmly combined together through this thermoplastic elastomer to provide an integral construction. Thus, the button mounting frame and the waterproof dust cover are combined into an integral construction, and therefore the efficiency of the assembling operation is enhanced.
According to the seventh aspect of the present invention, it is preferable that the skirt portion is smaller in thickness than a remaining portion of the waterproof dust cover. Accordingly, when the display switch button is pressed, a reaction force is low enough not to affect a switch-operating feeling.